Spring Perch & Shackle Clearance

johnr9q@yahoo.com

johnr9q@yahoo.com

Senior Member
Putting the car back together and attaching the spring perch to the spring with the shackle. The shackle goes into the spring with a tight fit but will not go into the spring perch. The spring perch diameter is .562 and the shakle diameter is .570, .008 interference. What should I do? I have another shackle that has a diameter of .540 which is pretty loose.
 

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johnr9q@yahoo.com said:
Putting the car back together and attaching the spring perch to the spring with the shackle. The shackle goes into the spring with a tight fit but will not go into the spring perch. The spring perch diameter is .562 and the shakle diameter is .570, .008 interference. What should I do? I have another shackle that has a diameter of .540 which is pretty loose.
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I assume you have rebushed the spring shackles.

Snyder’s sells a reamer for this (p/n A-5303R) but it’s expensive. I’ve found that I can clamp the shackle in a vise and use sandpaper to remove the black coating from around the shackle to get it to fit nicely. Start with 220 grit and finish up with say 320 then 400. It should slide in but no slop side to side. Burnish the spring side as well so it no longer feels “tight”. You won’t be removing much metal, you’re taking off the coating.

Be sure you don’t have any lip on the bushing interfering with the fit. You may have to lightly hit the end with a countersink to be sure.

Don’t forget to grease the shackle and bushing when you install it. A coat around it, then hit the grease fitting until it moushes out.

YB, do you know the proper diameter of the reamer?
 
Not sure, Bratton’s catalog sez to use a 14.5 mm drill bit.

If y’all still have your Bratton’s catalog, don’t throw them away. They have all kinds of useful information on fastener thread sizes and lengths. No other catalog has as much info except a MAC’s catalog.

BTW, old MAC’s catalog sez same, 14.5 mm.
 
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mathematically you are correct. it is the closest "drill bit" size to the .571 spec to ream the bushings for the springs and perches. I don't recommend using a drill bit as a reamer.
 
GRutter said:
mathematically you are correct. it is the closest "drill bit" size to the .571 spec to ream the bushings for the springs and perches. I don't recommend using a drill bit as a reamer.
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I am sure you are correct, but most of the vendors sell a 14.5 drill bit for reaming the spring bushings.
 
johnr9q@yahoo.com said:
JayJay, I also have another set of shackles that are .540 so they are very loose. What gives?
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I suppose it's possible that sometime in the past a vendor made up shackles and bushings that would fit together with a 0.540 shackle, even if they do not follow the original Ford specs. The bushings would have had a thicker wall than the OEM spec bushings.
 
If you want to use a fixed size reamer, not a drill, MSC Direct (mscdirect.com) has a 0.571" chucking reamer for about $65, about half the price you would pay for one from the Model A vendors. I have used this particular "brand" (the MSC Value Collection) for cutting tools in the past, and I think they're probably fine for the hobbyist who won't use them a lot. Not sure they'd be the best choice for a professional restoration or repair shop.

Adjustable reamers sound in principle to be a good idea, but if you have not used them regularly, be careful as it's pretty easy to get them set up so they don't have the same diameter from end to end. Also I've found that they can have a tendency to grab and rotate the bushings inside their housings, especially if you get them canted a bit upon entry. At that point you are pretty well screwed. You have to sneak up on the diameter you want.
 
I've used a wood dowel with a groove cut lengthwise, slid sandpaper into groove, wrapped it around dowel till a tight fit in hole needing honing, (not a critical honing), chucked it in a drill motor and a little light oil. Worked good, kind of a bush fix.
 
My experience is that, in this case, an adjustable reamer is a better choice. Single size reamers work well for bronze, brass, copper bushings such as used in distributor shaft housings or king pins. The spring shackles use steel bushings. Depending on the beginning internal size of the bushing, using a reamer that is set for to achieve a set final diameter may damage both the bushing and the reamer. Start with the adjustable reamer set to the initial size of the bushing and take numerous small cuts with a good cutting oil. Set the reamer just a bit tighter after each “cut”. Trial fit the shackle after each “cut” until you reach the desired close fit without binding through full travel of the shackle in the bushing.
 
bobbader said:
My experience is that, in this case, an adjustable reamer is a better choice. Single size reamers work well for bronze, brass, copper bushings such as used in distributor shaft housings or king pins. The spring shackles use steel bushings. Depending on the beginning internal size of the bushing, using a reamer that is set for to achieve a set final diameter may damage both the bushing and the reamer. Start with the adjustable reamer set to the initial size of the bushing and take numerous small cuts with a good cutting oil. Set the reamer just a bit tighter after each “cut”. Trial fit the shackle after each “cut” until you reach the desired close fit without binding through full travel of the shackle in the bushing.
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Exactly correct. And never ever turn the reamer backward-only forward,even when removing it.
 
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